Ford Repair: 1975 Ford Bronco 302, 1975 ford bronco, ford bronco

Question
Hi, I recently bought a 1975 Ford Bronco with a 302 and manual transmission.  It is all original with 40k miles.  It starts easily and runs very well for the first 10 minutes of driving (around a field slowly, as it isn't road worthy at this time).  However, after this 10 minute period the exhaust pipe gets visibly red-hot, and the engine bay is extremely hot, however the temperature gauge, which works, does not register an overheat.  At a certain point the engine will feel very weak and stall.  It will start again and idle but will not make nearly enough power to move.  This has only happened twice as I have only had to move it far twice.  I am thinking that it is either a lean carb or a timing problem.  Also right before this period, it will idle at a very high speed.  If you could give me your opinion I would be most appreciative.  
Thanks in advance,
Matthew Midei

Answer
MATTHEW

first i would check the exaust.if you are running a very short exaust it will cause red hot condition.your timiny will also cause this. timing should be between 6-8 degrees btdc. you are correct that a lean carb will also cause this problem. one more thing to check is to see if your carb is vapor locking.the next time you have this problem turn off the truck take off your breather and pump the carb 4-8 times fast then try to start. if it starts its vapor locking. take off carb and add a couple of gaskets.hope this helps.

ken